Architecture and urban infrastructure

Mohenjo-daro is a remarkable construction, considering its antiquity. It has a planned layout based on a grid of streets, which were laid out in perfect patterns. At its height the city probably had around 35,000 residents. The buildings of the city were particularly advanced, with structures constructed of same-sized sun dried bricks of baked mud and burned wood.
The public buildings of these cities also suggest a high degree of social organization. The so-called Great Granary at Mohenjo-daro as interpreted by Sir Mortimer Wheeler in 1950 is designed with bays to receive carts delivering crops from the countryside, and there are ducts for air to circulate beneath the stored grain to dry it. However, Jonathan Mark Kenoyer has noted that no record of grain exists at the "granary." Thus Kenoyer suggests that a more appropriate title would be "Great Hall."
Close to the granary, there is a building similarly civic in nature - a great public bath (sometimes called the Great Bath), with steps down to a brick-lined pool in a colonnaded courtyard. The elaborate bath area was very well built, with a layer of natural tar to keep it from leaking, and in the centre was the pool. Measuring 12m x 7m, with a depth of 2.4m, it may have been used for religious or spiritual ceremonies.
Within the city, individual homes or groups of homes obtained water from wells. Some of the houses included rooms that appear to have been set aside for bathing, and waste water was directed to covered drains lining the major streets. Houses opened only to inner courtyards and smaller lanes. A variety of buildings were up to two stories high.
Being an agricultural city, it also featured a large well, and central marketplace. It also had a building with an underground furnace (hypocaust), possibly for heated bathing.
Mohenjo-daro was a well fortified city. Lacking actual city walls, it did have towers to the west of the main settlement, and defensive fortifications to the south. Considering these fortifications and the structure of other major Indus valley cities like Harappa, lead to the question of whether Mohenjo-daro was an administrative centre. Both Harappa and Mohenjo-daro share relatively the same architectural layout, and were generally not heavily fortified like other Indus Valley sites. It is obvious from the identical city layouts of all Indus sites, that there was some kind of political or administrative centrality, however the extent and functioning of an administrative centre remains unclear.
Mohenjo-daro was successively destroyed and rebuilt at least seven times. Each time, the new cities were built directly on top of the old ones. Flooding by the Indus is thought to have been the cause of destruction.
The city was divided into two parts, the so-called Citadel and the Lower City. Most of the Lower City is yet to be uncovered, but the Citadel is known to have the public bath, a large residential structure designed to house 5,000 citizens and two large assembly halls.
Mohenjo-daro, Harappa and their civilization, vanished without trace from history until discovered in the 1920s. It was extensively excavated in the 1920s, but no in-depth excavations have been carried out since the 1960s.